Device for boiling sugar juices to crystals



DEVICE FOR BOILING SUGAR JUICES TO CRYSTALS Filed 001,. 23, 1935 g 24 I INVENTOR.

B J H. (:75: nsse Z5 ATTORNEYS.

Patented Dec. 8, 1936 UNITED STATES DEVICE FOR. Bounce SUGAR .mrcns' 'ro CRYSTALS Hermanus Andreus Ditmar Janene, Diokiakarta, Java, Dutch East Indies Application October 23, 1933, Serial No. 694,841 In the Netherlands November 15.1932

14 Claims.

For obtaining a quick and effective process for boiling sugar juices to crystals, it is highly important to have at any moment an indication of the condition of the boiling mass, in order to enable the operator to judge whether it is necessary for him to assist in the process by adding thick juice or syrup or by increasing or decreasing the supply of steam to the coil pipes, etc. Uncertainty in this respect will produce secondary crystallization and the crystals thus formed must be dissolved again by drawing in water. It is evident that this will cause a considerable loss of time and steam.

According to the present invention the boiling process is controlled and guided by indications obtained during the process concerning the transmission of heat between a metal vessel placed in the evaporating boiler, through which vessel steam is conducted, and the mother-liquor of the boiling mass.

, The invention will be further explained by means of the accompanying drawing illustrating a preferred device for applying the process.

In the drawing:

Figure 1 is a vertical section of the lower portion of an evaporating boiler fitted with the device of my invention.

Figure 2 is a sketch of a recording pressure device adapted to be used in my invention, and

Figure 3 is likewise a sketch of a recording temperature-pressure device which may be substituted for the pressure device of Fig. 2.

In a suitable place in the evaporating boiler as shown in Figure l where during the boiling process there is a .suflicient circulation of the boiling liquor as for instance in the central part there is arranged, preferably below the lowest level of the juice at which the initial quantity of the mass to be boiled is drawn in and which in Figure 1 is indicated by the dotted line H), a metal vessel (condensation vessel) 8, provided with a. steam inlet pipe 1 and an outlet for the water of condensation leading to a steam trap 9.

In the steam inlet pipe to the said vessel there are arranged outside the evaporating boiler and in the order given below, the following appendages, respectively devices:

(1) If desired, a common valve or cook I, for cutting off the steam supply, for instance for the 50 purpose of repair or control of other parts of the system;

(2) A reducing valve 2, for the purpose of reducing the steam supplied to a fairly constant pressure;

(3) If desired, a branch pipe with a controlling valve or throttle valve 5 for the purpose of conducting a desired part of the reduced pressure steam either to an area of constant lower pressure as, for instance, the outer air or else to a space containing steam of a variable lower. pressure as for instance the exhaust steam pipes.

The purpose of this branch pipe is to be able to adapt the quantity of steam passing the reducing valve 2, to the capacity at which the apparatus is working at its best.

In order to be sure of a constant discharge of steam through 5, in case this discharge takes place into a space with variable pressure as for instance the exhaust steam space, it is desirable that the reduced pressure and the highest pressure of the exhaust steam occurring in the working plant are with regard to each other at least in'the so-called critical pressure ratio, so that the fluctuations in the pressure of the exhaust steam have no more influence on the quantity of steam discharging through 5.

(4) If desired a common valve or cook 3 for the purpose of shutting off the steam of the condensation vessel 8 when the reducing apparatus remains operative;

(5) A controlling valve or throttle valve 4 for the purpose of admitting a desired quantity of reduced steam to the vessel 8 via the inlet pipe I;

(6) A recording pressure gauge or a common one, consequently approximately recording the pressure in the vessel 8 during. the boiling proc- After the operator las drawn as much juice or "masse cui into the evaporating. boiler as is necessary for the boiling in question and the condensation vessel 8 consequently liesbelow the level of liquid, the admission-valve 3 is opened. The valve l is always open; it is only closed for repair or control of the reducing valve 2 and for changing the throttle valve 5 if needed.

By the adjusted controlling valve or throttle valve 4 a certain quantity of. steam per unit of time will flow to the vessel 8where condensation occurs, after which the water of condensation is removed via the steam trap. 9.

The pressure which will occur in the condensation vessel 8 depends on the degree of facility with which the steam condenses against the wall of the vessel, that is to say ontheifacility with which the boiling mass absorbs" the condensation heat. There is, however, an exact relation between this facility and the concentration of the boiling, as the viscosity and the raising of the boiling point depend on this.

At the beginning of a boiling when the juice to be concentrated is still thin and the boiling point is only slightly raised, there is a strong exchange of heat so that the pressure inside the vessel 8 is low. As the concentration increases, the viscosity increases likewise and the boiling point is raised; the heat transmission is less facile under the influence of these factors which causes the steam pressure in the condensation 'vessel to rise. When a new quantity of Juice or syrup is drawn in, the pressure will, of course, go down and afterwards rise again.

The essential of the matter therefore is that when the boiling process is carried out under a given vacuum, the pressure on the pressure gauge 6 constitutes an indication of the condition of the boiling at any moment during the boiling process, so that the drawing in of juice or syrup and the supply of steam to the coil pipes may be regulated according to the indications of the pressure gauge. v

When using thedevice it will be possible after a little practice to boil the masses in a practically perfect manner along the desired line of supersaturation or refraction with a minimum use of steam, a minimum risk of conglomeration', a minimum amount of time and asuperior quality of sugar.

Instead of a pressure gauge either recording or not, a thermometer as shown in Figure 3, either recording or not may be provided in a ,suitable place. Figure 3 shows a vacuum Bourdon tube I 2' and a helical thermometer II with its extension tube 2| and bulb 25. The tips of the Bourdon tube and of the helix of the thermometer are connected by a system of levers in all respects identical with those in Figure 2 and designated by the same reference characters, primed. as the lever-system of Figure 2.

The Bourdon tube is connected to the vacuum space of the boiler and the bulb of the thermometer inserted in a suitable place where it will measure the temperature in vessel I, and can be so used because of the equivalence between the pressure and temperature of confined steam.

The invention further relates to a device for compensating the action of variations in the vac- ;uum in the evaporating boiler on the indications concerning the transmission of heat, since a va-,

' riation of the vacuum influences the speed of the circulation of the boiling, which, in its turn, causes variations in the heat transmission of the .metal vessel 0 and finally in the steam pressure.

a a In an ordinary recording pressure gauge this variation in pressure will be registered by the distance over which the pointer will then travel. The diagrams thus obtained will consequently produce an erroneous image of the condition of the boiling.

This disadvantage is removed by the pressure gauge shown in Figure 2 of the drawing according to the invention, which consists of two measuring devices, one of which 23 is connected to the steam inlet pipe of the metal condensation vessel and the other 22 to the vacuum space of the evaporating boiler, the said pressure gauge being so constructed that the distance travelled by the pointer and caused by the modification in the steam pressure as described above, is compensated by the distance travelled by the pointer on account of the variation in the vacuum.

This is possible, since, as found by experience the influence of the vacuum on the steam pressure within the vessel 8 is practically stable. It was found for instance, in a given case that a difference of 1 centimeter of vacuum causes a difference in steam pressure of about 0.037 atm. In this case the pressure gauge will be set in such a way that for '76 cm. of vacuum the pointer will have to travel over as great a distance as for a steam pressure of approx. 2.8 atm.

This moreover has the advantage that the diagrams of different boilers or factories, where operations take place with a different vacuum, can be immediately compared.

Fig. 2, exclusively as an example, represents an embodiment of the recording pressure gauge.

I I is a pressure spring connected to the steam inlet pipe to the metal vessel. It is a vacuum spring connected to the evaporating boiler. The

: pressure spring II is hingedly connected at I! by means of a rod M, with the pointer ll.

The vacuum spring I2 is hingedly and adjustably connected at 20 by means of the rods II, It and H to the pointer ll.

The rod Ii has a fixed fulcrum it. The rod l1, the length of which can be adjusted, is-hingedly and adiustably connected to the rod IS.

The pointer I3 is adapted to travel over a graduated rotating drum in order to record pressures.

When connecting the vacuum the point I! will act as a relative fixed fulcrum and the pointer will travel upward along the scale; one may, for instance, set the recording gauge so that for a vacuum of 76 centimetres the pointer will be at the point 50 on the scale. When connecting the steam pressure the point 20 will act as a relative fixed fulcrum and the pointer will likewise travel upwards along the scale.

In the above mentioned case the recording pressure gauge will be set in such a way that at 2.8 atm. the pointer also will be at the point 50 on the scale. At 76 centimetres of steam pressure and 2.8 atm. the pointer will therefore be at 100. When the apparatus is in operation and the vacuum due to certain factors, is raised by one centimetre, the steam pressure will be lowered by 0.037 atm.

The effect produced on the pointer by the pressure spring, is exactly compensated by the action of the vacuum spring. A

It is possible also, of course, when working with an evaporating boiler having a minimum vacuum of e. g. 45 centimetres (refined boilings at a high temperature) to let the vacuum spring only operate over the distance of 45-76 centimetres, in order to use the length of the graduated scale to better advantage.

It is also possible to bring about this compensation when using a thermometer instead of a recording steam pressure gauge.

I claim:

1. In a vacuum boiler for boiling sugar juice to crystallization, a controlling device which comprises a metallic vessel located within said boiler and beneath the lowest surface liquid level therein and having a steam inlet pipe and a steam outlet pipe the latter being closed by a steam trap, said inlet pipe embodying a reducing valve for producing constant steam supply pressure,

he vessel is a thermometer so located in the sys- 15 tem as to be subjected to the temperature conditions of the said metallic vessel.

3. The apparatus described in claim 1 in which the detector'of change connected with said metallic vessel is a recording thermometer so located in the system as to be subject to the temperature conditions of the said vessel.

4. The apparatus described in claim 1, in which the metallic vessel is in the central part of the boiler, and below the liquid level therein.

5. The apparatus of claim 1, in which the detector of change is a pressure gage attached to the steam inlet pipe, outside the boiler.

6. The apparatus of claim 1, in which the detector of change is a recording pressure gage attached to the steam inlet pipe, outside the boiler.

7. In a vacuum boiler for boiling sugar Juice to crystallization, a controlling device which comprises a metallic vessel located within said boiler and below the lowest liquid level thereof, said vessel having a steam inlet pipe and steam outlet pipe, the latter being closed by a steam trap, said inlet pipe having means establishing a uniform and determined steam supply pressure, and means for providing a constant supply of steam per unit of time, at that pressure, a detector of change of vacuum connected to the vacuum space of the vacuum pan, a detector of change of pres sure connected with the metallic vessel and means for combining the indications of said detectors to indicate variations of the rate of heat transfer between the sugar juice and the steam in the vessel.

8. The apparatus described in claim '7, in which the means combining the indications of said detectors of variations in the rate of heat transfer between the sugar juice and the steam in the vessel produces a record ofsuch variations.

9. In a vacuum boiler for boiling sugar juice to crystallization, a controlling device which comprises a metallic vessel located within the boiler and beneath the lowest liquid level thereof, a steam inlet pipe and a steam outlet pipe thereto, the latter closed by a steam trap, said inlet pipe being provided with means establishing a uniform and determined steam supply pressure, and means for providing a constant supply of steam per unit time at that pressure, an indicating device reacting to the vacuum in the boiler and connected with the boiler, a second indicating device reacting to the pressure of steam in the metallic vessel, connected with said metallic vessel, and a pointer so connected to said devices that the movement of the tip of the pointer due to movements of the said indicating device, connected with the metallic vessel, insofar as the said movement is caused by variation of vacuum in the boiler, is compensated by the movement of said pointer due to motion of the said indicating device connected with the boiler caused by variations in vacuum in said boiler.

10. In a vacuum boiler for boiling sugar juice to crystallization, a controlling device which comprises a metallic vessel located within said boiler and beneath the lowest liquid level thereof, a steam inlet pipe and a steam outlet pipe tl" ereto, the latter being closed by a steam trap, said inlet pipe being provided with means providing a uniform and determined steam supply pressure and means for providing a constant supply of steam per unit of time to said vessel at that pressure, a Bourdon tube connected with the vacuum space of said boiler, a thermometer arranged to determine the temperature in the steam vessel and means combining their respective indications to show alteration in the rate of heat exchange between the steam vessel and the vacuum pan.

11. In a vacuum boiler for boiling sugar juices to crystallization, a controlling device which comprises a metallic vessel within the boiler, and beneath the lowest liquid level thereof, steam inlet and steam outlet pipes connected therewith, the latter being closed by a steam trap, and the former having means providing a uniform and determined steam supply pressure, and means for supplying a constant amount of steam per unit of time, a Bourdon tube connected with the metallic vessel, a Bourdon tube connected with-the vacuum space of the boiler, a pointerpivotally connected intermediate its ends to the first named Bourdon tube and, intermediate this connection and its end pivotally and adjustably connected to the second Bourdon tube, the other end being arranged to move over an indicating scale.

12. In a vacuum boiler for boiling sugar juice to crystallization, a controlling device which comprises a metallic vessel located within said boiler and beneath the lowest liquid level thereof, a steam inlet pipe and a steam outlet pipe thereto the latter being closed by a steam trap, said inlet pipe being provided with means providing a uniform and determined steam supply pressure and means for providing a constant supply of steam per unit of time to said vessel at that pressure, a Bourdon tube connected with the vacuum space of said boiler, a thermometer arranged to determine the temperature in the steam vessel and a pointer so connected to said devices that the movement of the tip of the pointer due to the movement of the helix of the thermometer connected with the metallic vessel insofar as the said movement is caused by variation of the vacuum in the boiler is compensated by the movement of said pointer due to motion of the Bourdon tube connected with the boiler caused by variation in vacuum in said boiler.

13. In an apparatus for boiling sugar juice to crystallization, which comprises a vacuum pan and a controlling device which comprises a metallic vessel'within the boiler, and beneath the lowest liquid level thereof, steam inlet and steam outlet pipes connected therewith, the latter being closed by a steam trap, and the former having means providing a uniform and determined steam supply pressure and means for supplying a constant amount of steam per unit of time, a Bourdon tube connected to said metallic vessel, 9. Bourdon tube connected to the vacuum pan, a pointer pivotally and adjustably connected to the tip of said first Bourdon tube and pivotally and adjustably connected to the tip of said second Bourdon tube, a rotatable cylinder, means for rotating said cylinder, means for attaching a ruled chart thereto, said cylinder being so located with reference to said pointer that its point will trace a line upon said ruled chart, which line is the resultant of the separate movements of said pressure and vacuum Bourdon tubes.

14. In a vacuum boiler for boiling sugar juice to crystallization, a controlling device which comprises a metallic vessel within the boiler, and beneath the lowest liquid level thereof, a steam inlet and a steam outlet pipe connected therewith, the latter being closed by a steam trap, and the former having means providing a uniform and determined steam supply pressure, and means for supplying a constant amount of steam per unit of time, a spiral tube thermometer connected with the metallic vessel, a Bourdon tube connected with the vacuum space of the boiler, a pointer pivotally and adiustably connected to the tip of reference to said pointer that its point will trace the spiral tube 01' the thermometer and pivotaily a line upon said ruled chart, which line is the reand adjustably connected to the tip of the Boursultant of the separate movement or said helical don tube, a rotatable cylinder, means for rotatand Bourdon tube.

5 in: said cylinder, means for attaching a ruled chart thereto, said cylinder being so located with HERMANUS ANDREUS DITMARJANBBE. 

